Pros and cons of 1PSU Vs Multiple PSU

Summary:

Wanted to lay out the pros and cons of using 1 PSU vs Multiple PSU for a client having approx 100 LE and ~40 of them are Legal Employer.

Employment model is single assignment, they for sure are registered for each legal employer and need multiple TRUs.

There is no clear document to draw pros and cons across for each of them other than the recommendation to use 1 PSU which outlines the reasons to use 1 PSU but it doesn't outline any downside of using 1 PSU in any scenario or pluses to use multiple PSU

Can some one help with the pros and cons for 1 PSU and Multiple PSUs.